Twi may refer to:
- The Akan language spoken in Ghana
- Twi-, a numerical prefix
- Twi ba, a percussive musical instrument
- Twi'lek, an alien species in the Star Wars universe
TWI as an acronym may refer to:
- The Way International, a religious organization considered by some to be a cult
- The Welding Institute, a research and technology organisation based in the UK
- Trade weighted index, an economic instrument used to compare exchange rates
- Training Within Industry, a service in the US that provided consultancy to war-related industries during World War II
- Trans World International, a distributor and producer of televised sports
- TWI-Bus or Two Wire Interface, a variant of I²C
- Topographic Wetness Index, an algorithm based on slope and flow accumulation. Otherwise known as Compound Topographic Index
- Texting While Intoxicated, an iPhone/iPod Touch app where people share text messages from their intoxicated friends
- Two-Way Immersion is often used interchangeably with the term Dual language, which is a form of education in which students are taught literacy and content in two languages.
- Tread Wear Indicator
- Tolerable Weekly Intake